The present invention relates to an apparatus for testing leak detectors to insure that they are working properly. In more detail, the present invention relates to an apparatus for testing a pressure-actuated detector of leaks in a hose, pipe, or other conduit which is capable of both testing the leak detector and measuring actual flow rate of the detector.
The following description of the apparatus of the present invention will be made with reference to gasoline storage tanks and retail gasoline pumping equipment because that is perhaps the most likely application. However, those skilled in the art who have the benefit of this disclosure will recognize that the invention is equally useful in any application in which fluids are being pumped from a storage tank through a pipe, hose, or other conduit by a submerged or other type of pump which is equipped with a pressure-actuated device for testing for leaks in the pipe, hose, or conduit through which the fluid is pumped.
The underground gasoline storage tanks of gasoline service stations are equipped with pumps, usually submerged pumps, for pumping the gasoline up out of the tank, through a hose, and into a vehicle's gas tank. Leakage from those storage tanks is a serious environmental problem, and equally as serious, is a leak from the hose, pipe or other conduit through which the fuel is pumped for delivery to the vehicle's gas tank. To detect leaks between the dispenser at the end of the hose, pipe, or other conduit and the pump, a pressure-activated leak detector, generally including a diaphragm or piston-operated valve, is placed in the flow downstream of the pump. Such leak detectors are available from, for instance, The Marley Pump Company (Mission, Kans.) under the trademark "RED JACKET".
When pressure in the hose, pipe, or conduit of such an installation is less than about one psi and the submerged pump is turned on, a controlled amount of product (for instance, three gallons per hour) is metered though the leak detector into the piping system. If a leak is present that equals or exceeds this metered amount, as much product escapes from the system as is metered in through the leak detector. Under this condition, pressure cannot build up in the piping system. When a dispensing nozzle is opened to deliver the product to the vehicle, a poppet in the leak detector moves to a position that restricts the flow to approximately 1 or 11/2 to 3 gallons per hour. This restricted flow provides an indication to the operator that a leak is present in the line.
If there are no leaks, pressure rapidly builds in the system, forcing the leak detector to open to the full-flow position. In a system with no leaks, it takes only a matter of a few seconds to complete such a test. No further line testing takes place until the line pressure once again drops below one psi.
Recent government regulations now require annual testing of the leak detector to further insure that no leaks are present which exceed the maximum allowable rate. So far as is known, there is but one device available commercially which can provide quick and accurate testing of leak detectors That device, manufactured by Vaporless Manufacturing, Inc. (Prescott Valley, Ariz.) and sold as model number "LDT-880" is, however, characterized by a number of disadvantages which limit its utility. Specifically, that apparatus uses a needle valve and the submerged pump to simulate a three gph (or other flow rate) "leak" of product and requires the measurement of the volume which "leaks" to test the leak detector. Of course, that product is gasoline in the case of a leak detector installed in a gasoline storage tank such that the "leak" creates an unsafe condition; further, the requirement for an operator-read measurement creates a source of error. Most importantly, however, the tester is not "self-contained", e.g., it requires that testing be conducted on site because the use of the submerged pump to pump product through the "leak" is required.
The apparatus of the present invention, however, overcomes these disadvantages and limitations of that tester by providing a set of flow restrictors to allow testing at specified flow rates and given pressures which allows either a "yes" or "no" test of the condition of the leak detector. The apparatus also allows the measurement of actual flow rate by observation of the pressure produced by the detector across the restrictor. Further, the fluid which flows through the flow restrictors is preferably water. It is, therefore, an object of the present invention to provide such a tester.
Another object of the present invention is to provide a leak detector tester which is self-contained but which, if need be, can be operated by the pump submerged in a storage tank.
Another object of the present invention is to provide a leak detector tester which is safer to use than the only known commercially available leak detector tester.
Another object of the present invention is to provide a method of measuring the flow rate through a leak detector.
Other objects, and the advantages, of the present invention will be made apparent by the following detailed description of a presently preferred embodiment thereof.